IMC1f

IMC1f (PF3D7_1351700) is a Plasmodium falciparum alveolin that localizes to the basal complex during asexual blood-stage schizogony (PMID:41019501). Its recruitment is temporally restricted: IMC1f is undetectable at the early C-shaped initiation and enlargement steps of basal complex development, appearing only at the late 'separation' step and forming a complete ring at the onset of segmentation (PMID:41706859). IMC1f acts upstream of its paralog PfIMC1e, being required for the sequential recruitment of PfIMC1e to the basal complex, establishing a hierarchical targeting dependency between these two alveolins (PMID:41019501). Despite this role, IMC1f is individually dispensable for asexual replication, and combined loss of IMC1f and PfIMC1e produces no growth defect, indicating the two paralogs are not functionally redundant for asexual growth (PMID:41019501). Beyond its basal-complex localization, its recruitment hierarchy, and its predicted alveolin repeat architecture, no further mechanistic detail — including binding partners or the molecular basis of its recruitment — has been characterized for IMC1f in the available corpus.

1. 2014 Low

   Before functional data existed, the question was what structural class IMC1f belongs to; sequence analysis placed it in the alveolin family, framing it as a cytoskeletal/pellicle-associated protein.

   Evidence Computational domain and structural comparison of alveolin repeat sequences across Plasmodium family members

   PMID:25475193

   Open questions at the time

   • Computational prediction only, with no functional experimental validation specific to IMC1f
   • No experimental evidence that the tandem type 1/type 2 alveolin domains form the predicted structure
   • No cellular localization or interaction data at this stage
2. 2025 Medium

   It was unknown where IMC1f acts and whether it is essential; knockout established it localizes to the basal complex yet is individually dispensable and non-redundant with its paralog PfIMC1e for asexual replication.

   Evidence Direct gene knockout, DiCre/loxP conditional knockout, flow cytometry growth assay, and IFA with endogenous smHA tag in P. falciparum asexual blood stages

   PMID:41019501

   Open questions at the time

   • No growth phenotype leaves the specific asexual function of IMC1f undefined
   • Whether IMC1f contributes to sexual stages or transmission was not tested
   • No binding partners or biochemical activity identified
3. 2025 Medium

   The relationship between the two basal-complex alveolins was unknown; loss-of-function showed IMC1f is required for PfIMC1e recruitment, establishing a hierarchical assembly order.

   Evidence IFA of endogenous smV5-tagged PfIMC1e in the PfIMC1f knockout background, plus DiCre/loxP conditional knockout of PfIMC1e in P. falciparum

   PMID:41019501

   Open questions at the time

   • The molecular mechanism by which IMC1f enables PfIMC1e recruitment (direct binding vs. indirect scaffolding) is unresolved
   • Whether IMC1f recruits additional basal-complex components beyond PfIMC1e is unknown
   • No reciprocal test of whether PfIMC1e influences IMC1f localization reported here
4. 2026 Medium

   The timing of IMC1f arrival at the basal complex was unknown; high-resolution imaging placed its recruitment specifically at the late separation step, refining it as a marker of the mature, segmenting basal complex.

   Evidence Ultrastructure expansion microscopy (U-ExM) and DNA-PAINT nanoscale imaging of smV5-tagged IMC1f in a BTP2 inducible knockout background in P. falciparum

   PMID:41706859

   Open questions at the time

   • The trigger controlling IMC1f's late, separation-stage-specific recruitment is unknown
   • The functional consequence of ring formation at segmentation onset is not defined
   • Relationship between recruitment timing and the IMC1f→PfIMC1e hierarchy not directly integrated

• The direct molecular function of IMC1f — its binding partners, the structural basis of its basal-complex targeting, and its role (if any) in stages beyond asexual replication — remains unresolved.
• No direct interaction partners of IMC1f identified
• No structural or biochemical characterization of the alveolin domains in vitro
• Its function outside asexual blood stages, where it is dispensable, is untested